Multiple temperature refrigeration



NOV. 7, 1950 M F, BOOTH y 2,528,574

MULTIPLE TEMPERATURE REERTGERATION Filed June 10, 1946 Patented Nov. A1"; f

I UNIT-ED- srArasrArEn/lr OFFICE v 2,528,574 MULTIPLE TEMPERATURE REFmGERATroN Morris F. Booth, Alden, Mich.

Application June 10, 1946, Serial No. 675,601

This invention relates to multiple temperature refrigeration and is more particularly concerned with a system providing both a frozen food storage compartment and a normal refrigerated compartment wherein an improved system and control are incorporated. Y

It is an object of the present invention to provide a system of this character wherein the low temperature compartment is cooled by a refrigerant evaporator connected in the usual refrigerating circuit, which evaporator has means for circulating a secondary heat transfer liquid which in turn is led through the normal refrigerated food compartment having a heat ex.- changer therein. In systems of this character, the heat loads upon the two compartments may vary independently of one another and the refrigeration demand at one has no coordination with the demand at the other. Thus it may happen that both compartments demand refrigeration at about the same time and due to the temperature difference between them the circulation of heat transfer fluid tends to prevent the evaporator from properly bringing down the temperature in the low temperature compartment.

Thisis particularly true where the heat transfer uid and the refrigerant in the evaporator are in close relation for good heat transfer. Unless the evaporator is connected to a very powerful high side, it frequently occurs that the de mands of the high temperature compartment prevent the low temperature compartment from pulling down and in fact may tend to raise its temperature under these conditions.

lt is also an object of the present invention, therefore, to provide a control system which enables a small size high side to take care of the demand of both compartments and at the same time to prevent the low temperature compartment from ever getting above its predetermined desired temperature.

Figure 1 is a diagrammatic view of a refrig- 9 Claims. (Cl. 62-116) I4 connected to the usual high side I6 in a conventional refrigeration circuit I8. Y

The evaporator I4 is preferably formed of extruded metal having a cross section as illustrated at Figure 2. It will be seen that the extrusion is rectangular in cross sectional outline and has two parallel passages 20 and 22 extending continuously there-through. The passage 20 may form the evaporator and carry the refrigerant owing through the high side I6. The passage 22 being in intimate heat exchange relation with the passage 20 is adapted to be connected in a.v circuit carrying brine or other low temperature heat transfer fluid. This circuit comprising the conduits 26, 26 and 28 has a circulating pump 3B therein and also a heat exchanger 32 positioned in the compartment I2. The heat exchanger 32 may have provision for the usual ice trays 34. The pump 3l) may be driven by an electric motor -36 which is supplied from a power line 38 through conductors til. The motor is under the control of thermostatic switches 42 and it located in the compartments i9 and i2, respectively. The thermostat '32 is of the typel which closes when the temperature falls while the thermostat it is of the type which closes when the temperature rises. T he circuitfor the motor 36 is so arranged that both thermostats are in series with the motor which can only operate when both thermostats are closed.

In operation the high side (I6, which is of course provided with the usual thermostatic controls not illustrated, acts to maintain the temperature within compartment it between predetermined limits, for example, minus 5 to plus ll F. The switch i2 may be set to close at zero and to open at plus 5, while the switch 44 may be set to close erating system incorporating a preferred form at 30 and open at 25 assuming it to be mounted on the heat exchanger 32. Thus when the evaporator Il pulls down to a temperature of zero, the heat transfer circuit is then made available for, cooling the compartment I2 if such be necessary. As soon thereafter as the switch 44 closes by the temperature of heat exchanger 32 reaching 30, the circuit to motor 3 6 will be completed and pump 30 will operate to cause circulation of fluid through the conduits 24, 26 and 28 thus absorbing heat from the compartment I2 by the heat, n

exchanger'32 and transferring it to the fluid in the evaporator coil I4. As soon as the heat exchanger 32 pulls down to 25, switch Il opens, stopping this circulation. If y.it should happenl that the heat transferred to evaporator I4 were sufiicient to raise the temperature in compartment I0 above 5 F., switch 42 would open thus sagem 3 stopping the circulation of heat transfer duid until the high side I9 has an opportunity to again pull the compartment I down to zero.

While the system thus far described shows only Atwo compartments to be refrigerated, it may be used for as many additional compartments as desired and one way of so utilizing this system is indicated at the compartment 46. I-,This may be arportable unit such as an ice cream freezer having a heat exchanger 48 for handling the heat transfer iiuid and having a thermostatic switch Il similar to theswitch 44. The swi h 50 is adapted to be connected in Aparallel with the switch 44 by conductors 52 having a separable plug and socket 54 therein. The conduit 28 is provided with two T branches 56 between which is connected a thermostatic snap acting valve 59 responsive to the temperature in compartment I2. The heat exchanger 48 may be connected to the branches 56 by separable self-closing couplings 58 of the conventional type which operate to seal their opn ends when the couplings are disconnected thus retaining the fluid in the circuit. The operation of this portion of the circuit will be similar to that previously described.

The valve 59 may be set to open and close at ject only to the supervisory control of the both the compartments I2 and 46. If.

overcooling of compartment I2 is objectionable in a given installation, a suitable thermostatically A controlled by-pass around the heat exchanger 32 may be provided.

I claim:

1. In a two-temperature refrigeration system the combination of a low temperature evaporator in heat exchange relation to a compartment to be'cooled, means forming a path for a heat exchange liquid through said evaporator but isolated from the refrigerant therein, a heat exchanger in thermal relation to a second compartment to be cooled to a higherl temperature, a secondary fluid circuit comprising the heat exchanger, said means, and connecting conduits, electrically operated means for controlling now in the secondary circuit, electric means operatively associated with said electrically operated means to govern the same, and two thermostats in series with each other and with said electric means one responsive to evaporator temperature and vthe other rponsive-to heat exchanger temperature for governing said electric means to prevent uid ilow in the secondary circuit except when the evaporator is below a predetermined temperature and the heat exchanger is above a higher 2. In a two-temperature refrigeration system the combination of a low temperature evaporator in heat exchange relation to a compartment to be cooled, means forming a path for refrigerant and a heatexchange liquid through said evaporator, each path being isolated from the other, comprising a pair of adjacent coiled conduits with alternate passages for refrigerant and heat exchange fluid, a heat exchanger in thermal relation toa second compartment to be cooled to a higher temperature, a secondary fluid circuit for heat exchange fluid comprising the heat exchanger, one path of said means, and connecting conduits, electrically operated means for controlling the ilow in said circuit. electric means for governing said electrically operated means. and two thermostats in series with each other and with said electric means one responsive to evaporator temperature and the otherresponsive to heat exchanger temperature for governing said electric means to prevent uid flow in the secondary circuit except when the evaporator is below a predetermined temperature and the heat exchanger is above a higher predetermined temperature;

3. In a two-temperature refrigeration system the combination of a low temperature evaporator in heat exchange relation to a compartnent to be cooled, means forming a path for a, refrigerant and a heat exchange liquid throughsaid evaporator, each path being isolated from the other, comprising a pair of adjacent coiled conduits with alternate passages for refrigerant and heat exchange fluid formed in a homogeneous extruded metal bar, a heat exchanger in thermal relation to a: second compartment to be cooled to a higher temperature, connecting conduits between said heat exchanger and said means, a secondary uid circuit comprising the heat exchanger and one path of said means with connecting conduits, means for controlling iiow in the secondary circuit and two thermostats, one responsive to evaporator temperature andthe other responsive to heat exchanger temperature, for governing said last named means to prevent iiuid iiow in the secondary circuit except when the evaporator is below a predetermined temperature and the heat exchanger is above a higher predetermined temperature.

4. In a two-temperature refrigeration system l the combination of a low temperature evaporator in heat exchange relation to a compartment to be cooled, means forming a path for a heat exchange liquid through said evaporator but isolated from the refrigerant therein, a heat exchanger in thermal relation to a second compartment to be cooled to a higher temperature, a secondary duid circuit comprising the heat exchanger, said means, and connecting conduits, uid control means for causing movement of fluid through the secondary circuit, thermostatic means responsive to conditions at the higher temperature compartment for governing said uid control means and a second thermostatic means in series with said rst thermostatic means responsive to temperature at the evaporator governing said iiuld contro1 means to prevent initiation of flow except when the evaporator is below a lpredetermined temperature.

5. In a two-temperature refrigeration system the combination of a low temperature evaporator in heat exchange relation to a compartment to be cooled, means forming a Ipath for a heat exchange liquid through said evaporator but isolated from the refrigerant therein, a heat exchanger in thermal relation to a second compartment to be cooled to a higher temperature, a secondary uid circuit comprising the heat exchanger, said means, and connecting conduits, uid control means for causing fluid ow through the secondary circuit, means responsive to a predetermined rise in temperature at the high temperature compartment and means responsive to a predetermined low temperature at the evaporator for conjointly governing said fluid control means. Y

6. n a two-temperature refrigeration system the combination of a low temperature evaporator in heat exchange relation to a compartment to be cooled, means forming a path for a heat exchange liquid through said evaporator but isolated from the refrigerant therein, a heat exchanger in thermal relation to a second compartment to be cooled to a higher temperature, a secondary uid circuit comprising the heat exchanger, said means, and connecting conduits, an electrically driven pump lfor causing fluid now through the secondary circuit, thermostatic means responsive to conditions at the higher ternperature compartment for controlling said pump and a second thermostatic means responsive to temperature at the evaporator for preventing initiationof ow by said pump except when the evaporator is below a predetermined temperature.

'7. In a two-temperature refrigeration system the combination of a low temperature evaporator in heat exchange relation to a compartment to be cooled, means forming Ya path for a heat exchange liquid through said evaporator but isolated from the lrefrigerant therein, a heat exchanger in thermal relation to a second compartment to be cooled to a higher temperature, a secondary uid circuit comprising the heat exchanger, said means, and connecting conduits, an electrically driven pump for causing uid ow through the secondary circuit, means responsive to a predetermined rise in temperature at the high temperature compartment and means responsive to a predetermined low temperature at the evaporator for conjointly controlling said pump.

8. In a two-temperature refrigeration system -necting conduits being provided with two branches, a second heat exchanger removably connected to said branches, and a tertiary circuit including the second heat exchanger and said branches adapted to receive temporary shunted now of the heat exchange liquid from the secondary circuit at controled intervals.

9. In a two-temperature refrigeration system the combination of a low .temperature evaporator in heat exchange relation to a compartment to be cooled, means forming a path for a heat exchange liquid through said evaporator but isolated from the refrigerant therein, a heat exchanger in thermal relation to a second com partment to be cooled to a higher temperature, a secondary fluid circuit comprising the heat exchanger, said means, and connecting conduits, means responsive to temperatures at the evaporator and at the heat exchanger for regulating flow in the secondary circuit, and a tertiary heat exchange circuit paralleling said second circuit at one portion thereof removably associated with said heat exchanger, said tertiary circuit comprising means for detachably connecting uid passages in the tertiary circuit with the uid passages of the secondary circuit to receive temporaryshunted flow from said second circuit.

- MORRIS F. BOOTH.

REFERENCES CITED UNITED STATES PATENTS Name Date Higham Mar. 25, 1941 Number 

